// ----------------------------------------------------------------------------------
// Microsoft Developer & Platform Evangelism
// 
// Copyright (c) Microsoft Corporation. All rights reserved.
// 
// THIS CODE AND INFORMATION ARE PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND, 
// EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES 
// OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR PURPOSE.
// ----------------------------------------------------------------------------------
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// e-mail addresses, logos, people, places, and events depicted
// herein are fictitious.  No association with any real company,
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// places, or events is intended or should be inferred.
// ----------------------------------------------------------------------------------

using System;
using System.Collections.Generic;
using SL.IdentityModel.Protocols.WSTrust;

namespace SL.IdentityModel.Services
{
    /// <summary>
    /// Class caches tokens, bases on appliesTo, to be used in issuedToken calls
    /// </summary>
    public class TokenCache
    {
        private TimeSpan _allowedTimeSkew = new TimeSpan( 0, 5, 0 );
        private object _lock = new object();
        private Dictionary<string, RequestSecurityTokenResponse> _tokenCache = new Dictionary<string, RequestSecurityTokenResponse>();
        private bool _cacheEnabled = true;

        /// <summary>
        /// Allows disabling of the cache, if a new token should be used on each call
        /// </summary>
        public bool CacheEnabled
        {
            get { return _cacheEnabled; }
            set { _cacheEnabled = value; }
        }

        /// <summary>
        /// inserts a token into the cache
        /// </summary>
        /// <param name="appliesTo">appliesTo identifies the target service</param>
        /// <param name="rstr">Token response containing security token</param>
        public void AddTokenToCache( string appliesTo, RequestSecurityTokenResponse rstr )
        {
            lock ( _lock )
            {
                if ( _cacheEnabled )
                {
                    if ( HasTokenInCache( appliesTo ) )
                    {
                        _tokenCache.Remove( appliesTo );
                    }

                    _tokenCache.Add( appliesTo, rstr );
                }
            }
        }

        /// <summary>
        /// looks up a token base on the appliesTo provided
        /// </summary>
        /// <param name="appliesTo">appliesTo to identify the target service</param>
        /// <returns>RSTR, or null if no valid token is in the cache</returns>
        public RequestSecurityTokenResponse GetTokenFromCache( string appliesTo )
        {
            RequestSecurityTokenResponse token = null;

            lock ( _lock )
            {
                if ( HasTokenInCache( appliesTo ) && _cacheEnabled == true )
                {
                    token = _tokenCache[appliesTo];
                }
            }

            return token;
        }

        /// <summary>
        /// checks if an unexpired token is in the cache for the given appliesTO
        /// </summary>
        /// <param name="appliesTo">identifier for the target service</param>
        /// <returns>true if valid token is in cache, else false</returns>
        public bool HasTokenInCache( string appliesTo )
        {
            bool hasValidToken = false;

            lock ( _lock )
            {
                if ( _tokenCache.ContainsKey( appliesTo ) )
                {
                    RequestSecurityTokenResponse rstr = _tokenCache[appliesTo];

                    if ( ( rstr.Created < DateTime.Now.Add( _allowedTimeSkew ) && ( rstr.Expires > DateTime.Now.Add( _allowedTimeSkew ) ) ) )
                    {
                        hasValidToken = true;
                    }
                    else
                    {
                        _tokenCache.Remove( appliesTo );
                    }
                }
            }
            return hasValidToken;
        }
    }
}